Deck 15: Chemical Equilibrium

Question 1

Consider the two gaseous equilibria: SO₂(g)+ ¹/₂O₂(g) SO₃(g)K₁
2SO₃(g) SO₂(g)+ O₂(g)K₂
The values of the equilibrium constants K₁ and K₂ are related by

A)K₂ = K₁²
B)K₂² = K₁
C)K₂ = 1/K
D)K₂ = 1/K₁
E)none of these.

Answer 1

K₂ = 1/K

Question 2

The equilibrium constant expression for the reaction 2BrF₅(g) Br₂(g)+ 5F₂(g)is

A)K_c = [Br₂] [F₂] / [BrF₅]
B)K_c = [Br₂] [F₂]⁵ / [BrF₅]²
C)K_c = [Br₂] [F₂]² / [BrF₅]⁵
D)K_c = [BrF₅]² / [Br₂][F₂]⁵
E)K_c = 2[BrF₅]² / ([Br₂] * 5[F₂]⁵)

Answer 2

K_c = [Br₂] [F₂]⁵ / [BrF₅]²

Question 3

Equilibrium is established for the reaction 2X(s)+ Y(g) $\rarr$ 2Z(g)at 500K, K_c = 100. Determine the concentration of Z in equilibrium with 0.2 mol X and 0.50 M Y at 500K.

A)3.2 M
B)3.5 M
C)4.5 M
D)7.1 M
E)None of these.

Answer 3

7.1 M

Question 4

The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (least completion $\rarr$ greatest completion).
1)2NOCl 2NO + Cl₂ K_p = 1.7 * 10^{- 2}

2)N₂O₄ 11ec7153_21b4_20f5_88eb_03ce8bf4f194_TB3244_11 2NO₂ K_p = 1.5 * 10³

3)2SO₃ 11ec7153_21b4_20f5_88eb_03ce8bf4f194_TB3244_11 2SO₂ + O₂ K_p = 1.3 * 10 ^-5

4)2NO₂ 11ec7153_21b4_20f5_88eb_03ce8bf4f194_TB3244_11 2NO + O₂ K_p = 5.9 * 10 ^-5

A)2 < 1 < 3 < 4
B)3 < 1 < 4 < 2
C)3 < 4 < 1 < 2
D)4 < 3 < 2 < 1
E)4 < 3 < 1 < 2

Question 5

At 250ºC, the equilibrium constant K_p for the reaction PCl₅(g) PCl₃(g)+ Cl₂(g)is 1.80. Sufficient PCl₅ is put into a reaction vessel to give an initial pressure of 2.74 atm at 250ºC. Calculate the pressure of PCl₅ after the system has reached equilibrium.

A)1.50 atm
B)1.24 atm
C)4.24 atm
D)0.94 atm
E)1.12 atm

Question 6

If one starts with pure NO₂(g)at a pressure of 0.500 atm, the total pressure inside the reaction vessel when 2NO₂(g) 2NO(g)+ O₂(g)reaches equilibrium is 0.674 atm. Calculate the equilibrium partial pressure of NO₂.

A)0.152 atm
B)0.174 atm
C)0.200 atm
D)0.326 atm
E)The total pressure cannot be calculated because K_p is not given

Question 7

Calculate K_c for the reaction 2HI(g) H₂(g)+ I₂(g)given that the concentrations of each species at equilibrium are as follows: [HI] = 0.85 mol/L, [I₂] = 0.60 mol/L, [H₂] = 0.27 mol/L.

A)5.25
B)0.22
C)4.5
D)0.19
E)1.6 * 10²

Question 8

When the following reaction is at equilibrium, which of these relationships is always true?
2NOCl(g) 2NO(g)+ Cl₂(g)

A)[NO] [Cl₂] = [NOCl]
B)[NO]² [Cl₂] = [NOCl]²
C)[NOCl] = [NO]
D)2[NO] = [Cl₂]
E)[NO]² [Cl₂] = K_c[NOCl]²

Question 9

The equilibrium between carbon dioxide gas and carbonic acid is very important in biology and environmental science. CO₂(aq)+ H₂O(l) H₂CO₃(aq)
Which one of the following is the correct equilibrium constant expression (K_c)for this reaction?

A)
B)
C)
D)
E)

Question 10

3. 2NO₂ 2NO + O₂ K_p = 5.9 *10 ^-5

A)2 < 1 < 3
B)1 < 2 < 3
C)2 < 3 < 1
D)3 < 2 < 1
E)3 < 1 < 2

Question 11

The reaction A(g)+ 2B(g) C(g)was allowed to come to equilibrium. The initial amounts of reactants placed into a 5.00 L vessel were 1.0 mol A and 1.8 mol B. After the reaction reached equilibrium, 1.0 mol of B was found. Calculate K_c for this reaction.

A)0.060
B)5.1
C)17
D)19
E)25

Question 12

The brown gas NO₂ and the colorless gas N₂O₄ exist in equilibrium, 2NO₂ N₂O₄. In an experiment, 0.625 mole of N₂O₄ was introduced into a 5.00 L vessel and was allowed to decompose until equilibrium was reached. The concentration of N₂O₄ at equilibrium was 0.0750 M. Calculate K_c for the reaction.

A)7.5
B)0.125
C)0.0750
D)0.10
E)0.050

Question 13

Calculate K_p for the reaction 2NOCl(g) 2NO(g)+ Cl₂(g)at 400°C if K_c at 400°C for this reaction is 2.1 *10^-2.

A)2.1 * 10^-2
B)1.7 * 10^-3
C)0.70
D)1.2
E)3.8 * 10^-4

Question 14

At 35ºC, the equilibrium constant for the reaction 2NOCl(g) 2NO(g)+ Cl₂(g)is K_c = 1.6 *10^-5. An equilibrium mixture was found to have the following concentrations of Cl₂ and NOCl: [Cl₂] = 1.2 * 10^-2 M; [NOCl] = 2.8 * 10^-1 M. Calculate the concentration of NO(g)at equilibrium.

A)1.0 * 10^-4 M
B)1.0 * 10^-2 M
C)2.8 * 10^-1 M
D)2.4 * 10^-2 M
E)1.6 * 10^-3 M

Question 15

On analysis, an equilibrium mixture for the reaction 2H₂S(g) 2H₂(g)+ S₂(g)was found to contain 1.0 mol H₂S, 4.0 mol H₂, and 0.80 mol S₂ in a 4.0 L vessel. Calculate the equilibrium constant, K_c, for this reaction.

A)1.6
B)3.2
C)12.8
D)0.64
E)0.8

Question 16

Phosgene, COCl₂, a poisonous gas, decomposes according to the equation COCl₂(g) CO(g)+ Cl₂(g). Calculate K_p for this reaction if K_c = 0.083 at 900ºC.

A)0.125
B)8.0
C)6.1
D)0.16
E)0.083

Question 17

The equilibrium constant for the reaction Ni(s)+ 4CO(g) $\rarr$ Ni(CO)₄(g)is 5.0 * 10⁴ at 25ºC. What is the equilibrium constant for the reaction Ni(CO)₄(g) Ni(s)+ 4CO(g)?

A)2.0 * 10^-5
B)2.5 * 10⁹
C)5.0 * 10⁴
D)5.0 * 10^-4
E)2.0 * 10^-3

Question 18

Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic gases, phosgene and chlorine. CCl₄(g)+ ¹/₂O₂(g) COCl₂(g)+ Cl₂(g), K_c = 4.4 * 10⁹ at 1,000 K
Calculate K_c for the reaction 2CCl₄(g)+ O₂(g) 2COCl₂(g)+ 2Cl₂(g).

A)4.4 * 10⁹
B)8.8 * 10⁹
C)1.9 * 10¹⁰
D)1.9 * 10¹⁹
E)2.3 * 10^-10

Question 19

K_p for the reaction of SO₂(g)with O₂ to produce SO₃(g)is 3 * 10²⁴ . Calculate K_c for this equilibrium at 25ºC. (The relevant reaction is 2SO₂(g)+ O₂(g) 2SO₃(g).)

A)3 * 10²⁴
B)5 * 10²¹
C)2 * 10²⁰
D)5 * 10²²
E)7 * 10²⁵

Question 20

Which is the correct equilibrium constant expression for the following reaction? Fe₂O₃(s)+ 3H₂(g) 2Fe(s)+ 3H₂O(g)

A)K_c = [Fe₂O₃] [H₂]³ / [Fe]²[H₂O]³
B)K_c = [H₂] / [H₂O]
C)K_c = [H₂O]³ / [H₂]³
D)K_c = [Fe]²[H₂O]³ / [Fe₂O₃] [H₂]³
E)K_c = [Fe] [H₂O] / [Fe₂O₃] [H₂]

Question 21

For the nitrogen fixation reaction 3H₂(g)+ N₂(g) 2NH₃(g), K_c = 6.0 * 10^-2 at 500°C. If 0.250 M H₂ and 0.050 M NH₃ are present at equilibrium, what is the equilibrium concentration of N₂?

A)0.750 M
B)2.7 M
C)0.250 M
D)0.025 M
E)1.85 M

Question 22

Sodium carbonate, Na₂CO₃(s), can be prepared by heating sodium bicarbonate, NaHCO₃(s). 2NaHCO₃(s) Na₂CO₃(s)+ CO₂(g)+ H₂O(g)K_p = 0.23 at 100ºC
If a sample of NaHCO₃ is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC, what will the total gas pressure be?

A)0.46 atm
B)0.96 atm
C)0.23 atm
D)0.48 atm
E)0.11 atm

Question 23

At 700 K, the reaction 2SO₂(g)+ O₂(g) 2SO₃(g)has the equilibrium constant K_c = 4.3 * 10⁶, and the following concentrations are present: [SO₂] = 0.010 M; [SO₃] = 10. M; [O₂] = 0.010 M. Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is written), left to right or right to left, will the reaction proceed to reach equilibrium?

A)Yes, the mixture is at equilibrium.
B)No, left to right
C)No, right to left
D)There is not enough information to be able to predict the direction.

Question 24

At 700 K, the reaction 2SO₂(g)+ O₂(g) 2SO₃(g)has the equilibrium constant K_c = 4.3 * 10⁶ , and the following concentrations are present: [SO₂] = 0.10 M; [SO₃] = 10. M; [O₂] = 0.10 M. Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is written), left to right or right to left, will the reaction proceed to reach equilibrium?

A)Yes, the mixture is at equilibrium.
B)No, left to right
C)No, right to left
D)There is not enough information to be able to predict the direction.

Question 25

Hydrogen iodide decomposes according to the equation 2HI(g) H₂(g)+ I₂(g), for which K_c = 0.0156 at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC. Calculate the concentration of HI at equilibrium.

A)0.138 M
B)0.220 M
C)0.550 M
D)0.275 M
E)0.0275 M

Question 26

Consider the reaction N₂(g)+ O₂(g) 2NO(g), for which K_c = 0.10 at 2,000ºC. Starting with initial concentrations of 0.040 M of N₂ and 0.040 M of O₂, determine the equilibrium concentration of NO.

A)5.4 * 10^-3 M
B)0.0096 M
C)0.011 M
D)0.080 M
E)0.10 M

Question 27

For the reaction PCl₃(g)+ Cl₂(g) PCl₅(g)at a particular temperature, K_c = 24.3. Suppose a system at that temperature is prepared with [PCl₃] = 0.10 M, [Cl₂] = 0.15 M, and [PCl₅] = 0.60 M. Which of these statements is true?

A)The reaction is at equilibrium.
B)The reaction will proceed in the direction of forming more PCl₅ until equilibrium is reached.
C)The reaction will proceed in the direction of forming more PCl₃ and Cl₂ until equilibrium is reached.
D)None of the above statements is true.

Question 28

Consider the following reactions and their associated equilibrium constants: A + 2B C K₁
C 11ec7153_74a6_4277_88eb_656263c228fc_TB3244_11 D + E K₂
For the reaction A + 2B $\rarr$ D + E, having equilibrium constant K_c,

A)K_c = K₁ + K₂
B)K_c = K₁/K₂
C)K_c = K₁ - K₂
D)K_c = (K₁)(K₂)
E)K_c = K₂/K₁

Question 29

For the following reaction at equilibrium, which one of the changes below would cause the equilibrium to shift to the left? 2NOBr(g) 2NO(g)+ Br₂(g), $\Delta$ Hº_rxn = 30 kJ/mol

A)Increase the container volume.
B)Remove some NO.
C)Remove some Br₂.
D)Add more NOBr.
E)Decrease the temperature.

Question 30

For the reaction H₂(g)+ I₂(g) 2HI(g), K_c = 50.2 at 445ºC. If [H₂] = [I₂] = [HI] = 1.75 * 10^-3 M at 445ºC, which one of these statements is true?

A)The system is at equilibrium, thus no concentration changes will occur.
B)The concentrations of HI and I₂ will increase as the system approaches equilibrium.
C)The concentration of HI will increase as the system approaches equilibrium.
D)The concentrations of H₂ and HI will fall as the system moves toward equilibrium.
E)The concentrations of H₂ and I₂ will increase as the system approaches equilibrium.

Question 31

At 400ºC, K_c = 64 for the equilibrium H₂(g)+ I₂(g) 2HI(g). If 3.00 mol H₂ and 3.00 mol I₂ are introduced into an empty 4.0 L vessel, find the equilibrium concentration of HI at 400ºC.

A)0.15 M
B)1.2 M
C)2.4 M
D)4.8 M
E)5.8 M

Question 32

For the reaction SO₂(g)+ NO₂(g) SO₃(g)+ NO(g), the equilibrium constant is 18.0 at 1,200ºC. If 1.0 mole of SO₂ and 2.0 moles of NO₂ are placed in a 20. L container, what concentration of SO₃ will be present at equilibrium?

A)0.48 mol/L
B)0.11 mol/L
C)0.95 mol/L
D)2.22 mol/L
E)18 mol/L

Question 33

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br₂ concentration to decrease? 2NOBr(g) 2NO(g)+ Br₂(g), $\Delta$ Hº_rxn= 30 kJ/mol

A)Increase the temperature.
B)Remove some NO.
C)Add more NOBr.
D)Compress the gas mixture into a smaller volume.

Question 34

For the equilibrium reaction 2SO₂(g)+ O₂(g) 2SO₃(g), $\Delta$ Hº_rxn = -198 kJ/mol. Which one of these factors would cause the equilibrium constant to increase?

A)Decrease the temperature.
B)Add SO₂ gas.
C)Remove O₂ gas.
D)Add a catalyst.
E)None of these.

Question 35

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br₂ concentration to increase? 2NOBr(g) 2NO(g)+ Br₂(g), $\Delta$ Hº_rxn= 30 kJ/mol

A)Lower the temperature.
B)Remove some NO.
C)Remove some NOBr.
D)Compress the gas mixture into a smaller volume.

Question 36

At 340 K, K_p = 69 for the reaction H₂(g)+ I₂(g) 2HI(g). 50.0 g of HI is injected into an evacuated 5.00-L rigid cylinder at 340 K. What is the total pressure inside the cylinder when the system comes to equilibrium?

A)2.60 atm
B)1.76 atm
C)0.424 atm
D)2.18 atm
E)10.9 atm

Question 37

Hydrogen iodide decomposes according to the equation 2HI(g) H₂(g)+ I₂(g), for which K_c = 0.0156 at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC. Calculate the concentration of H₂ at equilibrium.

A)0.275 M
B)0.138 M
C)0.0275 M
D)0.0550 M
E)0.220 M

Question 38

Consider the following equilibria: 2SO₃(g) 2SO₂(g)+ O₂(g)K_c = 2.3 * 10^-7
2NO₃(g) 11ec7153_74a6_4277_88eb_656263c228fc_TB3244_11 2NO₂(g)+ O₂(g)K_c = 1.4 * 10^-3
Calculate the equilibrium constant for the reaction
SO₂(g)+ NO₃(g) $\rarr$ SO₃(g)+ NO₂(g)

A)78
B)1.3 * 10^-2
C)1.6 * 10^-4
D)3.2 * 10^-10
E)6.1 * 10³

Question 39

The reaction 2SO₃(g) 2SO₂(g)+ O₂(g)is endothermic. If the temperature is increased,

A)more SO₃ will be produced.
B)K_c will decrease.
C)no change will occur in K_c .
D)K_c will increase.
E)the pressure will decrease.

Question 40

For the following reaction at equilibrium, which choice gives a change that will shift the position of equilibrium to favor formation of more products? 2NOBr(g) 2NO(g)+ Br₂(g), $\Delta$ Hº_rxn = 30 kJ/mol

A)Increase the total pressure by decreasing the volume.
B)Add more NO.
C)Remove Br_2.
D)Lower the temperature.
E)Remove NOBr selectively.

Question 41

Consider this gas phase equilibrium system: PCl₅(g) PCl₃(g)+ Cl₂(g) $\Delta$ Hº_rxn = +87.8 kJ/mol.
Which of these statements is false?

A)Increasing the system volume shifts the equilibrium to the right.
B)Increasing the temperature shifts the equilibrium to the right.
C)A catalyst speeds up the approach to equilibrium and shifts the position of equilibrium to the right.
D)Decreasing the total pressure of the system shifts the equilibrium to the right.
E)Increasing the temperature causes the equilibrium constant to increase.

Question 42

A solution was prepared such that the initial concentrations of Cu²⁺(aq)and CN^-(aq)were 0.0120 M and 0.0400 M, respectively. These ions react according to the following chemical equation
Cu²⁺(aq)+ 4CN^-(aq) Cd(CN)₄^2-(aq)K_c = 1.0 * 10²⁵
What will be the concentration of CN^-(aq)at equilibrium?

Question 43

Consider this reaction at equilibrium: 2SO₂(g)+ O₂(g) 2SO₃(g), $\Delta$ Hº_rxn = -198 kJ/mol
If the volume of the system is compressed at constant temperature, what change will occur in the position of the equilibrium?

A)A shift to produce more SO₂
B)A shift to produce more O₂
C)No change
D)A shift to produce more SO₃

Question 44

For the reaction at equilibrium 2SO₃ 2SO₂ + O₂ ( $\Delta$ Hº_rxn= 198 kJ/mol), if we increase the reaction temperature, the equilibrium will

A)shift to the right.
B)shift to the left.
C)not shift.
D)The question cannot be answered because the equilibrium constant is not given.

Question 45

When the substances in the equation below are at equilibrium, at pressure P and temperature T, the equilibrium can be shifted to favor the products by CuO(s)+ H₂(g) H₂O(g)+ Cu(s) $\Delta$ Hº_rxn = -2.0 kJ/mol

A)increasing the pressure by means of a moving piston at constant T.
B)increasing the pressure by adding an inert gas such as nitrogen.
C)decreasing the temperature.
D)allowing some gases to escape at constant P and T.
E)adding a catalyst.

Question 46

Consider this reaction at equilibrium at a total pressure P₁: 2SO₂(g)+ O₂(g) 2SO₃(g)
Suppose the volume of this system is compressed to one-half its initial volume and then equilibrium is reestablished. The new equilibrium total pressure will be

A)twice P₁.
B)three times P₁.
C)3.5 P₁.
D)less than twice P₁.
E)unchanged.

Question 47

Consider the reaction N₂(g)+ 3H₂(g) 2NH₃(g). If nitrogen is added to the system at equilibrium, what will happen to the ammonia concentration?

Question 48

When the reaction 2H₂S(g) 2H₂(g)+ S₂(g)is carried out at 1065°C, K_p = 0.012. Starting with pure H₂S at 1065°, what must the initial pressure of H₂S be if the equilibrated mixture at this temperature is to contain 0.250 atm of H₂(g)?

A)1.06 atm
B)1.86 atm
C)0.94 atm
D)0.90 atm
E)1.52 atm

Question 49

The equilibrium constants for the chemical reaction N₂(g)+ O₂(g) 2NO(g)are K_P = 1.1 * 10^-3 and 3.6 *10^-3 at 2,200 K and 2,500 K, respectively. Which one of these statements is true?

A)The reaction is exothermic, $\Delta$ Hº < 0.
B)The partial pressure of NO(g)is less at 2,200 K than at 2,500 K.
C)K_P is less than K_c by a factor of (RT).
D)The total pressure at 2,200 K is the same as at 2,500 K.
E)Higher total pressure shifts the equilibrium to the left.

Question 50

A quantity of liquid methanol, CH₃OH, is introduced into a rigid 3.00-L vessel, the vessel is sealed, and the temperature is raised to 500K. At this temperature, the methanol vaporizes and decomposes according to the reaction CH₃OH(g) CO(g)+ 2 H₂(g), K_c= 6.90 * 10^-2.
If the concentration of H₂ in the equilibrium mixture is 0.426M, what mass of methanol was initially introduced into the vessel?

A)147 g
B)74.3 g
C)33.9 g
D)49.0 g
E)24.8 g

Question 51

If the reaction 2H₂S(g) 2H₂(g)+ S₂(g)is carried out at 1065°C, K_p = 0.0120. Starting from pure H₂S introduced into an evacuated vessel at 1065°C, what will the total pressure in the vessel be at equilibrium if the equilibrated mixture contains 0.300 atm of H₂(g)?

A)1.06 atm
B)1.36 atm
C)2.39 atm
D)4.20 atm
E)1.51 atm

Question 52

For the reaction 2NOCl(g) 2NO(g)+ Cl₂(g), K_c = 8.0 at a certain temperature. What concentration of NOCl must be put into an empty 4.00 L reaction vessel in order that the equilibrium concentration of NOCl be 1.00 M?

A)1.26 M
B)2.25 M
C)2.50 M
D)3.52 M
E)11.0 M

Question 53

Describe why addition of a catalyst does not affect the equilibrium constant for a reaction.

Question 54

Which of these situations will result if some CH₄(g)is removed from the reaction CO(g)+ 3H₂(g) CH₄(g)+ H₂O(g)at equilibrium?

A)H₂O will be consumed.
B)More CH₄ and H₂O will be produced.
C)K_p will decrease.
D)More CO will be produced.
E)No change will occur.

Question 55

The reaction 2NO(g) N₂(g)+ O₂(g)is exothermic, $\Delta$ Hº_rxn = -180 kJ/mol. Which one of these statements is true?

A)K_p at 1,000 K is less than K_p at 2,000 K.
B)K_p at 1,000 K is larger than K_p at 2,000 K.
C)The K_p's at 1000 K and 2000 K are the same.
D)K_p depends on total pressure as well as temperature.

Question 56

Consider the reaction N₂(g)+ 3H₂(g) 2NH₃(g). If hydrogen gas is added to this system at equilibrium, which direction will the reaction shift?

Question 57

A solution was prepared such that the initial concentrations of Cu²⁺(aq)and CN^-(aq)were 0.0120 M and 0.0400 M, respectively. These ions react according to the following chemical equation
Cu²⁺(aq)+ 4CN^-(aq) Cu(CN)₄^2-(aq)K_c = 1.0 * 10²⁵
What will be the concentration of Cu²⁺(aq)at equilibrium?

Question 58

In which of these gas-phase equilibria is the yield of products increased by increasing the total pressure on the reaction mixture?

A)CO(g)+ H₂O(g) CO₂(g)+ H₂(g)
B)2NO(g)+ Cl₂(g) 11ec7153_74a6_4277_88eb_656263c228fc_TB3244_11 2NOCl(g)
C)2SO₃(g) 11ec7153_74a6_4277_88eb_656263c228fc_TB3244_11 2SO₂(g)+ O₂(g)
D)PCl₅(g) 11ec7153_74a6_4277_88eb_656263c228fc_TB3244_11 PCl₃(g)+ Cl₂(g)

Question 59

Solid ammonium hydrogen sulfide is introduced into a 2.00-L flask, and the flask is sealed. If this solid decomposes according to the equation
NH₄HS(s)
NH₃(g)+ H₂S(g), K_p = 0.108 at 25°C,
What is the minimum mass of ammonium hydrogen sulfide that must be present in the flask initially if equilibrium is to be established at 25°C?

A)0.917 g
B)1.37 g
C)2.74 g
D)0.581 g
E)0.452 g

Question 60

For the common allotropes of carbon (graphite and diamond), C(gr) $\rarr$ C(dia)with equilibrium constant K = 0.32. The molar volumes of graphite and diamond are, respectively, 5.30 cm³/mol and 3.42 cm³/mol; $\Delta$ H_f of diamond is 1.90 kJ/mol. This data suggests that the formation of diamond is favored at

A)low temperatures and low pressures.
B)high temperatures and low pressures.
C)low temperatures and high pressures.
D)high temperatures and high pressures.

Question 61

The data below refer to the following reaction:
2NO(g)+ Br₂(g) 2NOBr(g) Find the concentration of NOBr when the system reaches equilibrium.

Question 62

Hydrogen iodide decomposes according to the equation:
2HI(g) H₂(g)+ I₂(g), K_c = 0.0156 at 400ºC
A 0.660 mol sample of HI was injected into a 2.00 L reaction vessel held at 400ºC.
Calculate the concentration of HI at equilibrium.

Question 63

The dissociation of solid silver chloride in water to produce silver ions and chloride ions has an equilibrium constant of 1.8 * 10^-18. Based on the magnitude of the equilibrium constant, is silver chloride very soluble in water? Why?

Question 64

Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon dioxide.
CaCO₃(s) CaO(s)+ CO₂(g)
K_P for this reaction is 1.16 at 800°C. A 5.00 L vessel containing 10.0 g of CaCO₃(s)was evacuated to remove the air, sealed, and then heated to 800°C. Ignoring the volume occupied by the solid, what will be the mass of the solid in the vessel once equilibrium is reached?

Question 65

Consider the chemical reaction 2NH₃(g) N₂(g)+ 3H₂(g). The equilibrium is to be established in a 1.0 L container at 1,000 K, where K_c = 4.0 * 10^-2. Initially, 1,220 moles of NH₃(g)are present. Estimate the equilibrium concentration of N₂(g).

Question 66

Consider the equilibrium equation C(s)+ H₂O(g)+ 2296 J CO(g)+ H₂(g). If additional gaseous water is added to this reaction mixture, what will happen to the temperature of the mixture?

Question 67

Consider the equilibrium equation C(s)+ H₂O(g)+ 2296 J CO(g)+ H₂(g). Which way will the reaction shift if the pressure on the system is increased?

Question 68

Hydrogen iodide decomposes according to the equation:
2HI(g) H₂(g)+ I₂(g), K_c = 0.0156 at 400ºC
A 0.660 mol sample of HI was injected into a 2.00 L reaction vessel held at 400ºC.
Calculate the concentration of H₂ equilibrium.

Question 69

The data below refer to the following reaction:
2NO(g)+ Br₂(g) 2NOBr(g) Calculate K_c.

Question 70

Ethanol and acetic acid react to form ethyl acetate and water according to the following chemical equation:
C₂H₅OH(l)+ CH₃COOH(l) CH₃COOC₂H₅(l)+ H₂O(l)
When two moles each of ethanol and acetic acid are combined, equilibrium is reached when two-thirds of a mole of each of the reactants remains. Calculate the equilibrium constant for this reaction assuming total volume does not change during the course of the reaction. (Note: since water is not the solvent, but rather a product of the reaction, [H₂O] changes during the course of the reaction, so it should be included in the equilibrium constant expression.)

Question 71

Consider the chemical reaction 2NH₃(g) N₂(g)+ 3H₂(g). The equilibrium is to be established in a 1.0 L container at 1,000 K, where K_c = 4.0 * 10^-2. Initially, 1,220 moles of NH₃(g)are present. Estimate the equilibrium concentration of H₂(g).

Question 72

The data below refer to the following reaction:
2NO(g)+ Br₂(g) 2NOBr(g) Find the concentration of Br₂ when the system reaches equilibrium.

Question 73

Consider the reaction N₂(g)+ 3H₂(g) 2NH₃(g). If we use a catalyst, which way will the reaction shift?

Question 74

Consider the reaction N₂(g)+ 3H₂(g) 2NH₃(g). If nitrogen is removed from the system at equilibrium, what will happen to the hydrogen (H₂)concentration?

Question 75

Consider the equilibrium equation C(s)+ H₂O(g)+ 2296 J CO(g)+ H₂(g). What will happen to the concentration of carbon monoxide if the temperature of this system is raised?

Question 76

What conditions are used in the Haber process to enhance the yield of ammonia? Explain why each condition affects the yield in terms of the Le Châtelier principle.

Question 77

Consider the chemical reaction 2NH₃(g) N₂(g)+ 3H₂(g). The equilibrium is to be established in a 1.0 L container at 1,000 K, where K_c = 4.0 * 10^-2. Initially, 1,220 moles of NH₃(g)are present. Calculate K_p for the reaction.

Question 78

Consider the reaction N₂(g)+ 3H₂(g) 2NH₃(g). The production of ammonia is an endothermic reaction. Will heating the equilibrium system increase or decrease the amount of ammonia produced?

Question 79

Consider the equilibrium equation C(s)+ H₂O(g)+ 2296 J CO(g)+ H₂(g). What will happen to the mass of carbon if we add gaseous water to the system?

Question 80

Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon dioxide.
CaCO₃(s) CaO(s)+ CO₂(g)
K_P for this reaction is 1.16 at 800°C. A 5.00 L vessel containing 10.0 g of CaCO₃(s)was evacuated to remove the air, sealed, and then heated to 800°C. Ignoring the volume occupied by the solid, what will be the overall mass percent of carbon in the solid once equilibrium is reached?